This invention relates in general to machines for holding and delivering flexible sheets, such as signatures, and more particularly to a stream feeding machine for delivering signatures to a binding machine
Printing magazines and similar publications involves a considerable amount of material handling. Large offset presses produce the printed material as folded signatures which are arranged in stacks by the machine. Workmen remove the stacks from the presses and deposit them on pallets on which they are stored as so-called hand lifts or the workmen may bind several short stacks of the signatures together with bands to form longer bundles or logs. Since the bands maintain the signatures under compression, the bundles or logs conserve storage space. In any event by storing the signatures, one or two presses may produce all the signatures that are required for a magazine.
Once all the signatures required for a magazine are available, they are assembled in the proper order to produce multiple copies of the magazine. Where a magazine contains relatively few pages or even a moderate number of pages, it will normally be assembled with a saddle binding, that is with the signatures in effect nested with their folds lying along essentially a common line. Staples are driven through the overlying folds at several locations to hold the signatures together as a magazine. Saddle binding machines exist for this purpose.
The typical saddle binding machine has inserter units arranged one after the other, with each unit having a pocket that holds no more than about one hand lift of signatures, which equates to a stack measuring about 8 to 14 inches high. Of course, the signatures differ from unit to unit, but within the pocket of any unit all of the signatures are the same. Behind the pocket of each unit lies a mechanism for extracting the signatures one at a time from the pocket and thereafter opening the signatures each with its fold presented upwardly. Indeed, the mechanism after opening a signature releases the signature and allows it to drop onto a chain which moves past the extracting mechanisms for all the inserter units. Thus, the signatures accumulate one over the other with their folds directly over the chain somewhat like a saddle. The pockets of the inserter units hold the signatures in an edge standing condition, but at about a 20.degree. degree angle to the vertical. A chain drive at the bottom of each pocket advances the signatures to an inclined back plate at the end of the pocket, and here the extracting mechanism withdraws the signatures, one after the other.
By reason of their relatively small capacity, the pockets of the inserter units in a saddle binding machine require frequent replenishment. Indeed, a single worker can only monitor and replenish about three pockets, so the typical saddle binding machine requires quite a few workers simply to fill the pockets of the machine as it operates. Moreover, the hand and arm motions required for placing hand lifts of signatures in an edge-standing condition in the pockets contribute to the physical disability known as carpal tunnel syndrome, which is very painful.
So-called stream feeders exist for automatically feeding signatures to the inclined pockets of saddle binding machines, but these machines move the signatures through a tortuous path where they go from edge-standing condition to a shingled condition, from which they are dropped one after the other into the pockets of the inserter units. These machines are quite complex and expensive.
The present invention resides in a stream feeder which holds signatures in an edge-standing condition as an array and moves those signatures generally horizontally and then at an angle, all while maintaining complete control over the signatures. It will feed the inclined pocket of an inserter unit automatically. Multiple stream feeders enable a single workman to attend to considerably more pockets so the binding machine can be operated with fewer attendants. The stream feeder to a large measure avoids the motions which contribute to carpal tunnel syndrome. It occupies little floor space and is generally inexpensive to operate.